KR102508435B1 - Preparation method for super absorbent polymer - Google Patents

Abstract

The present invention relates to a method for preparing a superabsorbent polymer. According to the manufacturing method of the super absorbent polymer of the present invention, a super absorbent polymer having an improved initial absorption rate can be provided.

Description

Manufacturing method of super absorbent polymer {PREPARATION METHOD FOR SUPER ABSORBENT POLYMER}

The present invention relates to a method for preparing a superabsorbent polymer. More specifically, it relates to a method for preparing a superabsorbent polymer having an improved initial absorption rate.

Super Absorbent Polymer (SAP) is a synthetic high-molecular substance that has the ability to absorb moisture 500 to 1,000 times its own weight. Material), etc., are named by different names. The superabsorbent polymer as described above has begun to be put into practical use as a sanitary tool, and now, in addition to sanitary products such as paper diapers and sanitary napkins for children, soil retaining agents for gardening, water retention materials for civil engineering and construction, sheets for raising seedlings, and freshness retainers in the food distribution field It is widely used as a material for steaming, steaming, etc.

In most cases, these superabsorbent polymers are widely used in the field of sanitary materials such as diapers and sanitary napkins. In addition, it is necessary to exhibit excellent permeability by maintaining its shape well even in a volume expansion (swelling) state by absorbing water.

However, it is known that it is difficult to improve both the water retention capacity (CRC), which is a physical property representing the basic absorption and water retention capacity of the superabsorbent polymer, and the absorbency under pressure (AUP), which represents the property of retaining moisture absorbed even under external pressure. . This is because when the overall crosslinking density of the superabsorbent polymer is controlled to be low, the water retention capacity may be relatively high, but the crosslinked structure becomes sparse and the gel strength is lowered, thereby reducing the absorbency under pressure. Conversely, when the absorbency under pressure is improved by controlling the crosslinking density to a high level, water is difficult to be absorbed between the dense crosslinked structures, and the basic water retention capacity may be deteriorated. For the above reasons, there is a limit to providing a superabsorbent polymer with improved water retention capacity and absorbency under pressure.

However, with the recent thinning of sanitary materials such as diapers and sanitary napkins, higher absorption performance is required for superabsorbent polymers. Among these, the simultaneous improvement of the water retention capacity and the pressure absorption capacity, which are opposite physical properties, and the improvement of the liquid permeability, etc. are emerging as important tasks.

In addition, after the surface of the super absorbent polymer applied to sanitary materials such as diapers or sanitary napkins absorbs liquid, the surface becomes damp to give an unpleasant feeling of use. To prevent this, the super absorbent polymer is required to exhibit a fast initial absorption rate. The faster the initial absorption rate, the more pleasant the use state can be maintained because the surface remains dry even after being swollen by the liquid.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a method for preparing a super absorbent polymer having a fast initial absorption rate.

In order to achieve the above object, according to one aspect of the present invention,

Forming a water-containing gel polymer by thermally or photopolymerizing a monomer composition including an acrylic acid-based monomer having an acidic group and at least partially neutralizing the acidic group, a carbonate foaming agent, a surfactant, an internal crosslinking agent, and a polymerization initiator;

pulverizing the water-containing gel polymer two or more times using a hole plate having a hole diameter of 8 to 15 mm;

preparing a base resin by drying the pulverized polymer; and

performing a surface crosslinking reaction on the base resin;

It provides a method for producing a superabsorbent polymer comprising a.

According to the manufacturing method of the superabsorbent polymer of the present invention, while exhibiting excellent absorbent properties, the initial rate of absorption An improved superabsorbent polymer can be provided.

Terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise", "comprise" or "having" are intended to indicate that there is an embodied feature, step, component, or combination thereof, but one or more other features or steps; It should be understood that the presence or addition of components, or combinations thereof, is not previously excluded.

Since the present invention can have various changes and various forms, specific embodiments will be exemplified and described in detail below. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Hereinafter, a method for preparing a superabsorbent polymer according to an embodiment of the present invention will be described in detail.

A method for producing a superabsorbent polymer according to an embodiment of the present invention,

Forming a water-containing gel polymer by thermally or photopolymerizing a monomer composition including an acrylic acid-based monomer having an acidic group and at least partially neutralizing the acidic group, a carbonate foaming agent, a surfactant, an internal crosslinking agent, and a polymerization initiator; pulverizing the water-containing gel polymer two or more times using a hole plate having a hole diameter of 8 to 15 mm; preparing a base resin by drying the pulverized polymer; and performing a surface crosslinking reaction on the base resin.

For reference, in the specification of the present invention, "polymer" or "polymer" means a state in which water-soluble ethylenically unsaturated monomers are polymerized, and may cover all moisture content ranges or particle size ranges. Among the polymers, a polymer having a water content (moisture content) of about 40% by weight or more in a state after polymerization and before drying may be referred to as a hydrogel polymer.

In addition, "base resin" or "base resin powder" refers to a polymer obtained by drying and pulverizing the polymer into a powder form, before performing a surface crosslinking step to be described later.

The water-containing gel polymer obtained by polymerization of acrylic acid-based monomers is commercially available as a superabsorbent polymer in powder form after going through processes such as drying, pulverization, classification, and surface crosslinking.

Recently, in superabsorbent polymers, not only various absorption properties such as absorbency and liquid permeability, but also how much dryness of the surface can be maintained in actual use of diapers has become an important criterion for estimating diaper characteristics.

The superabsorbent polymer obtained by the manufacturing method according to one embodiment of the present invention exhibits excellent overall absorption performance in terms of physical properties such as water retention capacity, absorbency under pressure, liquid permeability, etc. It was confirmed that the state can be maintained, leading to the present invention.

In the method for preparing the super absorbent polymer of the present invention, the monomer composition as a raw material of the super absorbent polymer includes an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group neutralized, a carbonate foaming agent, a surfactant, an internal crosslinking agent, and a polymerization initiator. includes

This will be described in more detail below.

First, the acrylic acid-based monomer is a compound represented by Formula 1 below:

[Formula 1]

R ¹ -COOM ¹

In Formula 1,

R ¹ is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond;

M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

Preferably, the acrylic acid-based monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.

Here, the acrylic acid-based monomer may have an acidic group and at least a portion of the acidic group may be neutralized. Preferably, those obtained by partially neutralizing the monomers with alkali substances such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide may be used. In this case, the degree of neutralization of the acrylic acid-based monomer may be 40 to 95 mol%, or 40 to 80 mol%, or 45 to 75 mol%. The range of the degree of neutralization may be adjusted according to final physical properties. However, if the degree of neutralization is too high, neutralized monomers may precipitate out, making it difficult for the polymerization to proceed smoothly. Conversely, if the degree of neutralization is too low, the absorbency of the polymer is greatly reduced, and it may exhibit properties such as elastic rubber that are difficult to handle. there is.

The concentration of the acrylic acid-based monomer may be about 20 to about 60% by weight, preferably about 40 to about 50% by weight, based on the monomer composition including the raw material of the superabsorbent polymer and the solvent, and the polymerization time and The concentration may be appropriate in consideration of the reaction conditions and the like. However, if the concentration of the monomer is too low, the yield of the superabsorbent polymer is low and economic problems may arise. Conversely, if the concentration is too high, a part of the monomer is precipitated or the pulverization efficiency of the polymerized water-containing gel polymer is low. Process problems may occur, and physical properties of the superabsorbent polymer may be deteriorated.

In the production method of the present invention, the monomer composition includes a carbonate foaming agent.

Foaming occurs during polymerization by the carbonate foaming agent to form pores in the water-containing gel polymer to increase the surface area and improve the initial absorption rate.

The carbonate foaming agent is, for example, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate, calcium bicarbonate , magnesium bicarbonate or magnesium carbonate can be used.

In addition, the carbonate foaming agent may be added in an amount of about 0.04 to about 0.5 parts by weight or about 0.2 to about 0.4 parts by weight based on 100 parts by weight of the acrylic acid monomer. If the amount of the carbonate foaming agent used exceeds 0.5 parts by weight, the number of pores increases too much, and the gel strength of the superabsorbent polymer decreases and the density decreases, causing problems in distribution and storage. In addition, when the amount is less than 0.04 parts by weight, the role as a foaming agent may be insignificant.

The monomer composition of the present invention includes a surfactant.

The surfactant may play a role of inducing uniform distribution of components in the monomer composition during polymerization and uniformly distributing the bubbles throughout the polymer while maintaining the shape of the bubbles formed by the foaming agent.

As the surfactant, an anionic surfactant, a nonionic surfactant, or a combination thereof may be used, preferably an anionic surfactant.

Examples of usable anionic surfactants include sodium dodecyl sulfate, sodium stearate, ammonium lauryl sulfate, sodium lauryl ether sulfate, sodium myreth sulfate, or alkyl ether sulfate-based compounds similar thereto. Anionic surfactants that can be used are not limited thereto, but sodium dodecyl sulfate or sodium stearate may be preferably used.

The surfactant may be added at a concentration of about 0.01 to about 0.1 parts by weight or about 0.03 to about 0.07 parts by weight based on 100 parts by weight of the acrylic acid monomer. If the concentration of the surfactant is too low, it is difficult to achieve the effect of improving the absorption rate because the role as a bubble stabilizer is insignificant. may or may not be desirable.

The monomer composition of the present invention includes an internal crosslinking agent. The internal crosslinking agent includes a crosslinking agent having at least one functional group capable of reacting with the acrylic acid monomer and at least one ethylenically unsaturated group; Alternatively, a crosslinking agent having two or more functional groups capable of reacting with substituents of the acrylic acid-based monomers and/or substituents formed by hydrolysis of the monomers may be used.

Specific examples of the internal crosslinking agent include N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, and propylene glycol di (meth) acrylate. )Acrylate, polypropylene glycol (meth)acrylate, butanedioldi(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanedioldi(meth)acrylate Acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerin tri(meth)acrylate, pentaerythyl At least one selected from the group consisting of stall tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, and ethylene carbonate may be used.

The internal crosslinking agent may be included in a concentration of about 0.01 to about 0.5% by weight based on the monomer composition to crosslink the polymerized polymer.

The polymerization initiator used during polymerization in the method for preparing the super absorbent polymer of the present invention is not particularly limited as long as it is generally used in the preparation of the super absorbent polymer.

Specifically, the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation according to a polymerization method. However, even with the photopolymerization method, since a certain amount of heat is generated by irradiation such as ultraviolet light irradiation and a certain amount of heat is generated according to the progress of the polymerization reaction, which is an exothermic reaction, a thermal polymerization initiator may be additionally included.

As the photopolymerization initiator, any compound capable of forming radicals by light such as ultraviolet light may be used without limitation in its configuration.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. Ketal), acyl phosphine, and alpha-aminoketone (α-aminoketone) may be used at least one selected from the group consisting of. On the other hand, as a specific example of acylphosphine, commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide (2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide) can be used. . More various photoinitiators are well described in 'UV Coatings: Basics, Recent Developments and New Applications (Elsevier 2007)' p115, a book by Reinhold Schwalm, and are not limited to the above examples.

The photopolymerization initiator may be included in a concentration of about 0.01 to about 1.0% by weight based on the monomer composition. If the concentration of the photopolymerization initiator is too low, the polymerization rate may be slowed down, and if the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent polymer may be small and physical properties may be non-uniform.

In addition, as the thermal polymerization initiator, at least one selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used. Specifically, examples of the persulfate-based initiator include sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), and ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), and examples of the azo-based initiator include 2, 2-azobis (2-amidinopropane) dihydrochloride, 2 , 2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride (2,2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride), 2- (carbamoyl azo) isobutyronitrile (2-(carbamoylazo)isobutylonitril), 2, 2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (2,2-azobis[2-(2-imidazolin-2- yl)propane] dihydrochloride), 4,4-azobis-(4-cyanovaleric acid), and the like. More various thermal polymerization initiators are well described in Odian's 'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the above examples.

In the manufacturing method of the present invention, the monomer composition of the superabsorbent polymer may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

Raw materials such as an acrylic acid-based monomer having an acidic group and neutralizing at least a portion of the acidic group, a photopolymerization initiator, a thermal polymerization initiator, an internal crosslinking agent, and additives may be prepared in the form of a monomer composition solution dissolved in a solvent.

The solvent that can be used at this time can be used without limitation in composition as long as it can dissolve the above-mentioned components, and for example, water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, Propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol At least one selected from ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N,N-dimethylacetamide may be used in combination.

The solvent may be included in a residual amount excluding the components described above with respect to the total content of the monomer composition.

On the other hand, the method of forming a water-containing gel polymer by thermal polymerization or photopolymerization of such a monomer composition is also not particularly limited as long as it is a commonly used polymerization method.

Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization according to the polymerization energy source. In the case of normal thermal polymerization, it can be carried out in a reactor having an agitation shaft such as a kneader, and in the case of photopolymerization, a movable Although it may proceed in a reactor equipped with a conveyor belt, the above polymerization method is an example, and the present invention is not limited to the above polymerization method.

For example, as described above, the water-containing gel polymer obtained by thermal polymerization by supplying hot air to a reactor such as a kneader equipped with an agitation shaft or heating the reactor is directed to the outlet of the reactor according to the shape of the agitation shaft provided in the reactor. The discharged water-containing gel polymer may be in the form of several centimeters to several millimeters. Specifically, the size of the obtained water-containing gel polymer may vary depending on the concentration and injection speed of the monomer composition to be injected, and a water-containing gel polymer having a weight average particle diameter of 2 to 50 mm can usually be obtained.

In addition, as described above, when photopolymerization is performed in a reactor equipped with a movable conveyor belt, the form of a water-containing gel polymer usually obtained may be a sheet-like water-containing gel polymer having the width of a belt. At this time, the thickness of the polymer sheet varies depending on the concentration and injection rate of the monomer composition to be injected, but it is preferable to supply the monomer composition so that a polymer sheet having a thickness of about 0.5 to about 5 cm can be obtained. When the monomer composition is supplied to such an extent that the thickness of the polymer on the sheet is too thin, production efficiency is low, which is undesirable. When the thickness of the polymer on the sheet exceeds 5 cm, the polymerization reaction does not occur evenly over the entire thickness due to the excessively thick thickness. may not be

At this time, the water-containing gel polymer obtained in this way may have a normal water content of about 40 to about 80% by weight. Meanwhile, throughout the present specification, "moisture content" refers to a value obtained by subtracting the weight of the dry polymer from the weight of the hydrogel polymer as the content of moisture with respect to the total weight of the hydrogel polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation in the polymer during drying by raising the temperature of the polymer through infrared heating. At this time, the drying condition is a method of raising the temperature from room temperature to about 180 degrees and then maintaining it at 180 degrees, and the total drying time is set to 20 minutes including 5 minutes of the temperature raising step, and the moisture content is measured.

Next, a step of pulverizing the obtained hydrogel polymer is performed. The pulverization may be performed twice or more on the water-containing gel polymer.

When the water-containing gel polymer is pulverized by applying a certain shear stress, the original morphology of the water-containing gel polymer is deformed, and intaglio-shaped irregularities are formed on the surface.

According to the manufacturing method of the present invention, the polymerization conditions are optimized by the above-described method and the conditions in the grinding step described later are adjusted to bring about a transformation of the hydrogel morphology, thereby exhibiting excellent overall absorption properties and having a fast initial absorption rate. A quality superabsorbent polymer can be manufactured.

According to one embodiment of the present invention, the crushing step may be performed by pushing the hydrogel polymer through a hole plate in which a plurality of holes having a certain diameter are formed. At this time, as an extruder used to extrude the water-containing gel polymer, a single or multiple screw type extruder may be used.

Meanwhile, the physical properties of the polymer after grinding are changed according to the degree of shear stress applied to the water-containing gel polymer in the grinding step. The inventors of the present invention focused on the fact that the shear stress applied in the grinding step varies depending on the rotational speed of the grinding device, the diameter of the hole of the perforated plate, and the number of grinding, and pulverization that can obtain a polymer with optimized physical properties by adjusting the above variables conditions were found.

Based on the research results of the inventors of the present invention, while maintaining the rotation speed of the grinding device at 1000 to 1100 rpm, the hydrogel polymer is pushed through a perforated plate having holes having a diameter of 8 to 15 mm or less. It is pulverized in a manner, and such pulverization can be carried out twice or more, for example, 2 to 3 times. It was confirmed that the superabsorbent polymer subjected to the pulverization step to satisfy the above conditions can exhibit optimized physical properties in terms of absorption rate and initial absorption rate.

If the number of grinding is less than 2 times, it is difficult to improve the initial absorption rate, and if grinding more than 3 times, process steps are unnecessarily increased, which is not preferable in terms of productivity.

In addition, the diameter of the hole of the perforated plate may be 8 mm or more, or 9 mm or more, or 10 mm or more, or 11 mm or more and 15 mm or less, or 14 mm or less. If the diameter of the hole is smaller than 8 mm, particles may aggregate with each other during the grinding process or residual monomers may be generated, and if the hole diameter is larger than 15 mm, the surface may be irregularly shrunk during the subsequent drying process, resulting in the final resin. There is a problem in that the quality becomes uneven and the effect of improving the absorption rate cannot be exhibited.

Next, a step of drying the pulverized polymer through the pulverization step described above is performed.

A drying temperature in the drying step may be about 150 to about 250 °C. When the drying temperature is less than 150 ° C, the drying time is too long and there is a risk of deterioration in the physical properties of the finally formed super absorbent polymer, and when the drying temperature exceeds 250 ° C, only the surface of the polymer is excessively dried, resulting in a subsequent pulverization process There is a concern that fine powder may be generated in the water, and physical properties of the finally formed superabsorbent polymer may be deteriorated. Therefore, preferably, the drying may be performed at a temperature of about 150 to about 200 °C, more preferably at a temperature of about 160 to about 180 °C.

Meanwhile, the drying time may be about 20 to about 90 minutes in consideration of process efficiency, but is not limited thereto.

As long as the drying method of the drying step is also commonly used as a drying process for hydrogel polymers, the composition may be selected and used without limitation. Specifically, the drying step may be performed by a method such as hot air supply, infrared ray irradiation, microwave irradiation, or ultraviolet ray irradiation. The water content of the polymer after the drying step may be about 0.1 to about 10% by weight.

Next, a step of pulverizing the dried polymer obtained through such a drying step into a powder form is performed.

The polymer powder obtained after the grinding step may have a particle size of about 150 to about 850 μm. The grinder used for grinding to such a particle size is specifically, a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, or a jog mill. A jog mill or the like may be used, but the present invention is not limited to the above examples.

In addition, in order to manage the physical properties of the superabsorbent polymer powder to be finalized after the pulverization step, a separate process of classifying the polymer powder obtained after pulverization according to the particle size may be performed, and the polymer powder is prepared at a certain weight ratio according to the particle size range. can be classified so that

Next, a surface crosslinking reaction may be performed on the pulverized polymer by further performing a surface crosslinking reaction on the polymer obtained as described above, that is, the base resin.

The surface crosslinking reaction is a step of forming a superabsorbent polymer having more improved physical properties by inducing a crosslinking reaction on the surface of the pulverized polymer in the presence of a surface crosslinking agent. Through this surface crosslinking reaction, a surface crosslinking layer is formed on the surface of the pulverized polymer, that is, the base resin.

The surface crosslinking reaction may be performed by a conventional method for increasing the crosslinking density of the surface of the polymer particle, for example, by mixing a solution containing a surface crosslinking agent and the pulverized polymer for a crosslinking reaction. there is.

Here, the surface crosslinking agent is a compound capable of reacting with a functional group of the polymer, and its structure is not particularly limited. However, as a non-limiting example, the surface crosslinking agent is ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether , ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, propanediol, dipropylene glycol, polypropylene glycol, glycerin, polyglycerin, butanediol, heptanediol, hexanediol trimethylolpropane, pentaerythricol, It may be one or more compounds selected from the group consisting of sorbitol, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, iron hydroxide, calcium chloride, magnesium chloride, aluminum chloride, and iron chloride.

At this time, the content of the surface crosslinking agent may be appropriately adjusted depending on the type of crosslinking agent or reaction conditions, and may be preferably adjusted to 0.001 to 5 parts by weight based on 100 parts by weight of the pulverized polymer. If the content of the surface crosslinking agent is excessively low, surface modification may not be performed properly, and physical properties of the final resin may be deteriorated. Conversely, if an excessive amount of the surface crosslinking agent is used, it is undesirable because the absorbency of the resin may rather decrease due to an excessive surface crosslinking reaction.

On the other hand, the surface crosslinking reaction step includes a method of mixing the surface crosslinking agent and the pulverized polymer in a reaction tank, a method of spraying the surface crosslinking agent on the pulverized polymer, and continuously mixing the pulverized polymer and the surface crosslinking agent in a continuously operated mixer. It can be carried out by a conventional method such as supplying and mixing.

In addition, water may be additionally added when adding the surface crosslinking agent. As such, since the surface crosslinking agent and water are added together, even dispersion of the surface crosslinking agent can be induced, agglomeration of polymer particles can be prevented, and penetration depth of the surface crosslinking agent into the polymer particles can be further optimized. Considering these objects and effects, the amount of water added together with the surface crosslinking agent may be adjusted to 0.5 to 10 parts by weight based on 100 parts by weight of the pulverized polymer.

In addition, the surface crosslinking reaction step may be performed at a temperature of 100 to 250 °C. In addition, the surface crosslinking reaction may proceed for 1 minute to 120 minutes, preferably 1 minute to 100 minutes, and more preferably 10 minutes to 60 minutes. That is, the surface crosslinking reaction step may be performed under the above-described conditions in order to induce a minimum surface crosslinking reaction and prevent polymer particles from being damaged and deteriorating physical properties during excessive reaction.

The superabsorbent polymer prepared by the manufacturing method of the present invention may have a fast initial absorption rate and 1 minute tap water absorption capacity without deteriorating physical properties such as water retention capacity and absorbency under pressure.

For example, the superabsorbent polymer prepared by the above manufacturing method has a water retention capacity (CRC) of about 28 g/g or more, or about 29 g/g or more, or about 30 g/g, measured according to EDANA method WSP 241.3 or greater, but may range from about 40 g/g or less, or about 38 g/g or less, or about 35 g/g or less.

In addition, the superabsorbent polymer prepared by the above manufacturing method has an absorbency under load (AUP) of 0.7 psi of about 10 g/g or more, or about 12 g/g or more, or about 14 g/g or more, as measured according to WSP 242.3 of the EDANA method. g or greater, but less than or equal to about 18 g/g, or less than or equal to about 17 g/g, or less than or equal to about 16 g/g.

In addition, the superabsorbent polymer prepared by the above manufacturing method may have a vortex time of about 30 seconds or less, about 27 seconds or less, or about 24 seconds or less. The absorption rate is excellent as the value is small, and the lower limit of the absorption rate is 0 seconds in theory, but may be, for example, about 10 seconds or more, about 15 seconds or more, or about 17 seconds or more.

The absorption rate refers to the time (time, unit: seconds) at which the vortex of the liquid disappears due to rapid absorption when the superabsorbent polymer is added to physiological saline and stirred, and the shorter the time, the higher the superabsorbent polymer can be seen as having a fast initial absorption rate.

In addition, the superabsorbent polymer prepared by the above manufacturing method has an absorption capacity (g) of tap water for 1 minute measured according to the following formula 1 of about 145 g or more, or about 148 g or more, or about 150 g or more and about 200 g or less. , or about 190 g or less, or about 180 g or less.

[Equation 1]

Tap water 1 minute absorption capacity (g) = W - B

In Equation 1 above,

W put 1 ± 0.0005 g of the superabsorbent polymer sample into a non-woven fabric bag, put the non-woven fabric bag into a 2 L plastic bottle, add 1 L of 24 tap water into the non-woven fabric bag, leave it for 1 minute, then take it out and leave it in the air for 1 minute is the weight of the non-woven fabric bag measured after drying, and B is the weight of the dry non-woven fabric.

Tap water used in the evaluation of physical properties has an electrical conductivity of 170 to 180 μS/cm. Since the electrical conductivity of tap water has a great influence on the measured physical properties, it is necessary to measure the physical properties using tap water having the same electrical conductivity.

As described above, the superabsorbent polymer of the present invention has excellent absorbency and particularly has a fast initial absorption rate, so that high-quality sanitary materials can be provided.

The present invention is explained in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Example>

Manufacture of superabsorbent polymer

Example 1

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.30 g of sodium bicarbonate (SBC) as a foaming agent, 0.03 g of sodium dodecyl sulfate (SDS) as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water were mixed to prepare an aqueous monomer composition. When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 11 mm in a perforated plate (opening ratio: 38%) twice It was carried out to prepare a crumb.

The obtained resin was spread on a stainless wire gauze having a hole size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100), and each classification was 10/65/23 in weight ratio /2 (#20-30/#30-50/#50-100/#100 or less) to obtain a base resin powder.

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

Example 2

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, A monomer aqueous solution composition was prepared by mixing 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.30 g of SBC as a foaming agent, 0.03 g of SDS as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water. . When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 11 mm in a perforated plate (opening ratio: 38%) 3 times It was carried out to prepare a crumb. The obtained gel-type resin was spread on a stainless wire gauze having a pore size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100), and each classification was 10/65/23 in weight ratio /2 (#20-30/#30-50/#50-100/#100 or less) to obtain a base resin powder.

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

Comparative Example 1

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, A monomer aqueous solution composition was prepared by mixing 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.30 g of SBC as a foaming agent, 0.03 g of SDS as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water. . When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 11 mm in a perforated plate (opening ratio: 38%) 1 time It was carried out to prepare a crumb. The obtained gel-type resin was spread on a stainless wire gauze having a pore size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100/), and each classification was 10/65/ The base resin powder was obtained by mixing at 23/2 (#20-30/#30-50/#50-100/#100 or less).

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

Comparative Example 2

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, A monomer aqueous solution composition was prepared by mixing 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.30 g of SBC as a foaming agent, 0.03 g of SDS as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water. . When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 16 mm in a perforated plate (opening ratio: 38%) 1 time It was carried out to prepare a crumb. The obtained gel-type resin was spread on a stainless wire gauze having a pore size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100), and each classification was 10/65/23 in weight ratio /2 (#20-30/#30-50/#50-100/#100 or less) to obtain a base resin powder.

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

Comparative Example 3

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, A monomer aqueous solution composition was prepared by mixing 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.30 g of SBC as a foaming agent, 0.03 g of SDS as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water. . When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 16 mm in a perforated plate (opening ratio: 38%) 1 time After implementation, the grinding process (chopping) was performed once at a rotational speed of 1050 rpm using a meat chopper having a hole diameter of 11 mm in a perforated plate (opening ratio: 38%) Further progress was made to prepare a crumb. The obtained gel-type resin was spread on a stainless wire gauze having a pore size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100), and each classification was 10/65/23 in weight ratio /2 (#20-30/#30-50/#50-100/#100 or less) to obtain a base resin powder.

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

Comparative Example 4

100 g of acrylic acid, 0.6 g of polyethylene glycol diacrylate (PEGDA, Mw=523) as a crosslinking agent, 0.008 g of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide as a photoinitiator, A monomer aqueous solution composition was prepared by mixing 0.10 g of sodium persulfate (SPS) as a thermal initiator, 0.03 g of SDS as a surfactant, 123.3 g of 31.5% caustic soda (NaOH), and 38.53 g of water. When the neutralization liquid is cooled and the final temperature reaches 40 ° C, the aqueous monomer solution composition is received in a tray, and then ultraviolet rays are irradiated with a UV irradiation device while maintaining the polymerization atmosphere temperature at 80 ° C (irradiation amount: 10 mW / cm ² ) , UV polymerization was performed for 1 to 3 minutes to prepare a hydrogel polymer sheet.

After taking out the polymerized sheet and cutting it into a size of 3 cm x 3 cm, chopping at a rotational speed of 1050 rpm using a meat chopper with a hole diameter of 11 mm in a perforated plate (opening ratio: 38%) was carried out twice to prepare a crumb. The obtained gel-type resin was spread on a stainless wire gauze having a pore size of 600 μm to a thickness of about 30 mm and dried in an oven capable of varying air volume up and down. Hot air at 185 ° C. was flowed from the bottom to the top for 15 minutes and from the top to the bottom for 15 minutes to uniformly dry, and after drying, the water content of the dried body was set to 2% or less. After drying, it was pulverized with a grinder, and then classified at an Amplitude of 1.5 mm for 10 minutes (classification mesh combination: #20-30/#30-50/#50-100), and each classification was 10/65/23 in weight ratio /2 (#20-30/#30-50/#50-100/#100 or less) to obtain a base resin powder.

Then, to 100 parts by weight of the base resin prepared above, 0.096 parts by weight of fumed silica, 0.019 parts by weight of ethylene glycol diglycidyl ether (EX-810), surface crosslinking solution (7.7 parts by weight of water, 4.8 parts by weight of methanol, After evenly mixing 0.048 parts by weight of sodium metabisulfite and 0.19 parts by weight of aluminum sulfate 18 hydrate (Al-S), a surface crosslinking reaction was performed at 140 ° C. for 35 minutes. After the surface treatment was completed, a superabsorbent polymer having an average particle diameter of 150 to 850 μm was obtained using a sieve.

Thereafter, 0.096 parts by weight of Aerosil (A200) was dry mixed with the prepared superabsorbent polymer.

<Experimental example>

The physical properties of the superabsorbent polymers prepared in Examples and Comparative Examples were evaluated in the following manner.

Unless otherwise indicated, all of the following physical property evaluations were conducted at room temperature (25° C.), and physiological saline or saline means a 0.9 wt% sodium chloride (NaCl) aqueous solution.

In addition, tap water used was one having electrical conductivity of 170 to 180 μS/cm when measured using Orion Star A222 (Company: Thermo Scientific).

(1) Centrifuge Retention Capacity (CRC)

The water retention capacity by water absorption capacity under no load of each resin was measured according to EDANA WSP 241.3.

Specifically, the superabsorbent polymer W ₀ (g) (about 0.2 g) was uniformly put into a bag made of nonwoven fabric, sealed, and immersed in physiological saline (0.9% by weight) at room temperature. After 30 minutes, water was drained from the bag for 3 minutes under the condition of 250 G using a centrifuge, and the mass W ₂ (g) of the bag was measured. Moreover, after carrying out the same operation without using resin, the mass _W1 (g) at that time was measured. Using each obtained mass, CRC (g/g) was calculated according to the following equation.

[Equation 1]

CRC (g/g) = {[W ₂ (g) - W ₁ (g)]/W ₀ (g)} - 1

(2) Absorbency under Pressure (AUP)

The absorbency under pressure of 0.7 psi of each resin was measured according to the EDANA method WSP 242.3.

Specifically, a stainless steel 400 mesh wire mesh was attached to the bottom of a plastic cylinder having an inner diameter of 60 mm. Under conditions of room temperature and 50% humidity, superabsorbent polymer W ₀ (g) (0.9 g) is uniformly sprayed on a wire mesh, and a piston capable of uniformly applying a load of 0.7 psi thereon is slightly larger than the outer diameter of 60 mm. It is small and has no gaps with the inner wall of the cylinder, so that up and down movement is not hindered. At this time, the weight W ₃ (g) of the device was measured.

A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed inside a petro dish having a diameter of 150 mm, and physiological saline solution composed of 0.9% by weight sodium chloride was leveled with the top surface of the glass filter. One sheet of filter paper having a diameter of 90 mm was placed thereon. The measuring device was placed on a filter paper, and the liquid was absorbed for 1 hour under a load. After 1 hour, the measuring device was lifted up and its weight W ₄ (g) was measured.

Using each obtained mass, the absorbency under load (g/g) was calculated according to the following formula.

[Equation 2]

AUP(g/g) = [W ₄ (g) - W ₃ (g)]/W ₀ (g)

(3) Absorption rate (Vortex time)

The absorption rate (vortex time) was measured in seconds according to the method described in International Publication No. 1987-003208.

Specifically, 2 g of superabsorbent polymer was added to 50 mL of physiological saline at 23 ° C to 24 ° C, and the magnetic bar (diameter 8 mm, length 31.8 mm) was stirred at 600 rpm until the vortex disappeared. was calculated by measuring in seconds.

(4) Tap water absorption capacity

According to Equation 1 below, tap water absorption capacity (g) was measured for 1 minute.

[Equation 1]

Tap water 1 minute absorption capacity (g) = W - B

In Equation 1 above,

For W(g), put 1 ± 0.0005 g of the superabsorbent polymer sample into a non-woven fabric bag, put the non-woven fabric bag into a 2 L plastic container, add 1 L of 24 tap water into the non-woven fabric bag, leave it for 1 minute, take it out, and It is the weight of the non-woven fabric bag measured after being left in the air for 1 minute, and B(g) is the weight of the non-woven fabric in a dry state.

At this time, when measured using Orion Star A222 (Company: Thermo Scientific), tap water having an electrical conductivity of 170 to 180 μS/cm was used.

In addition, when measuring the tap water absorption capacity, samples classified as #40-50 were used when measuring the base resin, and when measuring the superabsorbent polymer finally obtained after surface crosslinking, samples of the entire particle diameter range were used without classification.

Among the physical property values of the Examples and Comparative Examples, the base resin before surface crosslinking is shown in Table 1, and the superabsorbent polymer finally obtained after surface crosslinking is shown in Table 2, respectively.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 CRC (g/g) 34.5 34.2 34.9 35.2 34.3 35.7 Vortex time (seconds) 32 27 47 52 43 55 1 minute tap water absorption capacity
(g) 166 180 153 135 158 101

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 CRC (g/g) 29.9 29.5 30.2 30.5 30.0 31.0 0.7 AUP (g/g) 14.6 15.0 14.2 13.9 14.4 15.8 Vortex time (seconds) 24 21 31 35 29 40 1 minute tap water absorption capacity
(g) 151 162 140 119 144 89

Referring to Tables 1 and 2, it was confirmed that the Examples of the present invention exhibited faster absorption rates than Comparative Examples when measured by the vortex method and when measuring the water absorption capacity for 1 minute. Also, this trend was maintained both before and after the surface crosslinking step. On the other hand, in the case of Comparative Examples 1 to 3 out of the grinding conditions of the present invention or Comparative Example 4 in which a carbonate foaming agent was not used during polymerization, both the initial absorption rate and the absorption rate by the vortex method were much worse than those of the examples of the present invention. Able to know.

Claims (8)

Forming a water-containing gel polymer by thermally or photopolymerizing a monomer composition including an acrylic acid-based monomer having an acidic group and at least partially neutralizing the acidic group, a carbonate foaming agent, a surfactant, an internal crosslinking agent, and a polymerization initiator;
pulverizing the water-containing gel polymer two or more times using a hole plate having a hole diameter of 8 to 15 mm;
preparing a base resin by drying the pulverized polymer; and
performing a surface crosslinking reaction on the base resin;
including,
pulverizing the water-containing gel polymer two or more times; Grinding twice or more is independently using a hole plate having a hole diameter of 8 to 15 mm,
Manufacturing method of superabsorbent polymer.
According to claim 1,
The carbonate foaming agent is sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium bicarbonate, calcium bicarbonate, magnesium A method for producing a superabsorbent polymer comprising at least one selected from the group consisting of bicarbonate and magnesium carbonate.
According to claim 1,
The carbonate foaming agent is included in 0.04 to 0.5 parts by weight based on 100 parts by weight of the acrylic acid monomer, a method for producing a super absorbent polymer.
According to claim 1,
The surfactant is sodium dodecyl sulfate, sodium stearate, ammonium lauryl sulfate, sodium lauryl ether sulfate, and sodium myreth sulfate ( A method for producing a superabsorbent polymer comprising at least one selected from the group consisting of sodium myreth sulfate).
According to claim 1,
The surfactant is included in 0.01 to 0.1 parts by weight based on 100 parts by weight of the acrylic acid-based monomer, a method for producing a super absorbent polymer.
According to claim 1,
The method of manufacturing a super absorbent polymer having a diameter of 11 to 15 mm of the hole of the perforated plate.
According to claim 1,
The super absorbent polymer has a vortex time of 30 seconds or less.
According to claim 1,
The superabsorbent polymer has an absorption capacity (g) of tap water for 1 minute measured according to Equation 1 below of 145g or more.
[Equation 1]
Tap water 1 minute absorption capacity (g) = W - B
In Equation 1 above,
For W(g), put 1 ± 0.0005 g of the superabsorbent polymer sample into a non-woven fabric bag, put the non-woven fabric bag into a 2 L plastic container, add 1 L of 24 tap water into the non-woven fabric bag, leave it for 1 minute, take it out, and The weight of the nonwoven bag measured after being left in the air for 1 minute,
B(g) is the weight of the dry nonwoven fabric.